The invention relates to an absorption water cooing and heating apparatus and a high temperature regenerator therefor, and more particularly to an absorption water cooling and heating apparatus, in which lithium bromide is used for an absorbent and water is used for a refrigerant, and a high temperature regenerator therefor.
With a conventional absorption water heater/chiller, for example, as shown in Japanese Patent Unexamined Publication No. 8-193767, a liquid chamber serving as a liquid reservoir for storing an absorption solution is formed in upper and lower portions of a combustion chamber, through which a combustion gas generated in a burner of a high temperature regenerator flows, and a plurality of solution tubes for communication between the upper liquid chamber and the lower liquid chamber are provided to extend through the combustion chamber. These solution tubes can be largely classified into two groups.
One of the groups provides a tube group which is positioned near the burner and against which flame strikes, and the other of the groups provides a tube group positioned apart from the burner. A space where the solution tubes do not stand close together is defined between the two groups. Then, flame issuing from the burner is caused to strike against the group of liquid tubes, which are positioned near the burner, to decrease in temperature. Thus, reduction of nitrogen oxide (NOx) generated in the high temperature regenerator is achieved.
Hereupon, with the high temperature regenerator of the absorption water heater/chiller described in Japanese Patent Unexamined Publication No. 8-193767, the solution tubes are circular in cross sectional shape, so that liquid and vapor flow only in one direction from a lower side to an upper side. That is, a one-dimensional flow, in which a boiled rising flow goes throughout the entire tubes, is only generated.
When combustion is effected with the flame of the burner near the group of solution tubes, which stand close together in the combustion chamber, the combustion gas is high in temperature at those regions of the solution tubes, with which flame contacts, to provide a high heat flux. In the case where a circular tube is used for the solution tubes, an increase in heat flux leads to an increase in amount of vapor generated in the tubes to cause an increased flow resistance. As a result, the solution circulating in the solution tubes is reduced amount, and the solution becomes locally high in concentration. An experimental study carried out by the inventors of the present application has revealed that corrosive deterioration is generated in those portions of the solution tubes, in which the solution becomes locally high in concentration. Accordingly, it is not possible to use an inexpensive material, and so use of an extremely expensive high temperature regenerator is unavoidable.
Further, in Japanese Patent Unexamined Publication No. 9-42800 discloses an absorption water heater/chiller, in which forced convection is generated by passing a dilute solution, supplied from a solution pump, through a group of heat transfer tubes having a high heat flux and disposed near the burner. However, when partially loaded, the absorption water heater/chiller is operated with an amount of circulating solution throttled in the high temperature regenerator, thus causing a disadvantageous that partial load operation cannot be effected in the construction described in the above publication, in which forced convection applies for the high temperature regenerator.
Further, Japanese Patent Unexamined Publication No. 8-49802 discloses a high temperature regenerator for an absorption water cooing and heating apparatus, in which Karman""s vortices are generated with a relationship Pxe2x89xa72D where P indicates a pitch of a group of liquid tubes in a fuel or air flow direction and D indicates a diameter D of the liquid tubes, and mixing of flame is promoted by the Karman""s vortices. With the construction described in the above publication, the Karman""s vortices are generated to cause mixing of unburned gases which makes the combustion gas uniform in temperature. However, since the combustion gas decreases uniformly in temperature, CO is reduced in a rate of oxidation reaction. Hereupon, to eliminate CO through oxidization, there is caused a need of providing a space which is useful for oxidization of CO but not for heat transfer, in a downstream side of the group of liquid tubes.
The invention has been made in view of the disadvantage of the prior art described above, and an object of the invention is to achieve both of reduction of thermal NOx and restriction of CO generation in an absorption water heater/chiller. Another object of the invention is to make an absorption water heater/chiller and a high temperature regenerator therefor compact. A further object of the invention is to realize an inexpensive and long-life absorption water heater/chiller and a high temperature regenerator therefor. Still further object of the invention is to realize an absorption water heater/chiller capable of stably operating even under a partly loaded condition, and a high temperature regenerator therefor.
The invention provides an absorption water heater/chiller comprising a high temperature regenerator and a low temperature regenerator for heating an absorption solution, which is generated by having an absorbent absorbing a refrigerant, and for evaporating the refrigerant to concentrate the absorption solution; a condenser for condensing a refrigerant vapor generated in the low temperature regenerator at the time of cooling; an evaporator mounting therein a heat transfer tube for circulation of a heating medium and for exchanging heat between a liquid refrigerant generated in said condenser or a vapor refrigerant generated in said high temperature regenerator and with the heating medium in said heat transfer tube; and an absorber communicated with the evaporator and for having the absorption solution, which has concentrated in said high temperature regenerator and said low temperature regenerator, absorbing the refrigerant vapor introduced from said evaporator, and wherein said high temperature regenerator comprises an inner cylinder, an outer cylinder, which covers said inner cylinder, and combustion means mounted to said outer cylinder and for burning a combustible gas in said inner cylinder, and wherein a plurality of first flat tubes, which are lengthy in a flow direction of a combustion gas, are provided near the combustion means, and a plurality of second flat tubes, which are lengthy in the flow direction of the combustion gas, are provided in a downstream side of the first flat tubes in the flow direction of the combustion gas, fins being formed on outer surfaces of said second flat tubes.
More desirably, fins are formed partly on flat portions of the second flat tubes; a combustion space for the combustion gas is defined between the first flat tubes and the second flat tubes; a distance between the combustion means and the plurality of first flat tubes is 10 to 100 mm; portions for receiving the absorption solution are formed on upper and lower portions of the inner cylinder between the inner cylinder and the outer cylinder, and the first flat tubes and the second flat tubes are communicated with the receiving portions; and the plurality of first flat tubes are arranged in two rows in the flow direction of the combustion gas.
According to the invention, a high temperature regenerator for absorption water heaters/chillers comprises an inner cylinder; an outer cylinder which covers the inner cylinder; liquid chambers formed between the outer cylinder and the inner cylinder in upper and lower portions of the inner cylinder and for holding a solution; a burner mounted to said outer cylinder and for burning a combustible gas in said inner cylinder; and a plurality of first solution tubes arranged in said inner cylinder to be communicated with said upper liquid chamber; and wherein the burner has a flame hole plate toward the inner cylinder surface, and a distance between the flame hole plate and the first solution tubes is set to 10 mm to 100 mm.
More desirably, a plurality of second solution tubes are arranged downstream of the first solution tubes to be communicated with the upper liquid chamber, and the first solution tubes are flat tubes, which are flat in a direction of flame from the burner; the first solution tubes are constructed such that temperature boundary layers are formed to extend from the upstream side to the downstream side along the flow direction of the combustion gas; the first solution tubes are communicated with said lower liquid chamber; the second solution tubes are communicated with the lower liquid chamber; a plurality of fins are formed on outer surfaces of the second solution tubes; and the second solution tubes are a flat tube which is lengthy in the flow direction of the combustion gas.